A number of antibodies were screened for binding to human peripheral neutrophils and one was identified (31D8) which binds herterogeneously, identifying two different populations of neutrophils. Using this antibody and flow cytometry we found tht neutrophils which are 31D8-positive express a unique receptor for and respond to stimulation by the chemoattractant f met-leu-phe with membrane potential depolarization, generation of supeoroxide anion, and chemotaxis. 31D8-negative cells do not respond or exhibit chemotaxis, unless they are first "primed" in vitro. After "priming" these 31D8-negative cells express the same unique receptor as the 31D8-positive cells, though they do not express the 31D8 antigen. This evidence clearly demonstrates there are two types of neutrophils circulating in the peripheral blood of humans with different functional capacity which are likely to be modulated in vivo. In other studies we have investigated the role of surface carbohydrate in neutrophil "priming" using the lectin wheat germ agglutinin (WGA). WGA stimulates neutrophils to depolarize, produce superoxide, hydrogen peroxide, and aggregate, as does f met-leu-phe. In addition, there is a specific synergy between WGA and f met-leu-phe which results in a substantial increase superoxide/hydrogen peroxide production, not seen with other agents. In related studies methods were developed to measure the oxidative burst and secretion of azurophil granule contents by neutrophils using flow cytometry. This has enabled us to simultaneously measure either of these functions as well as two other parameters (such as binding of stimulating ligand, antibody binding, membrane potential response, or intracellular calcium levels).